The conversion of lignin in batch processes using hydrogen and catalysts is known. For example, Boocock, D. G. B et al, “The Production of Synthetic Organic Liquids from Wood Using a Modified Nickel Catalyst” discloses exposing air dried poplar to hydrogen and Raney Nickel in a batch autoclave at 340° C. to 350° C. for 1 or 2 h to produce “oil products”. However, according to Boocock et al, “[t]he use of Raney nickel has now been abandoned in favour of nickel from nickel salts . . . .”
The use of catalysts to recover lignin is also known. Zakzeski, Pieter C., et al; “The Catalytic Valorization of Lignin for the Production of Renewable Chemicals”, 2010 is a comprehensive review of catalytic efforts to convert lignin.
While many have proposed theoretical continuous processes, the inventors are not aware of any disclosure which is enabling beyond a theoretical basis. For example, converting solid lignin presents significant handling problems as documented in PNNL-16079, September 2006.                “High-pressure feeding systems for biomass slurries have been recognized as a process development issue at least as long as the modern biomass conversion systems have been under development since the Arab oil embargo of 1973. The authors review the state of the art and various slurry pumping systems, the vast majority of which include ball check valves. Their conclusion is that high-pressure feeding remains a problem for small scale production but believe “the high-pressure feeding of biomass slurries should be more readily achieved at larger flow rates wherein the fibrous nature of the biomass would not be expected to bridge and plug the orifices and valves.”        
There exists therefore the need to provide a pumping and charging scheme for slurries.
An example of this is in the series of applications US 2011/0312051, US 2011/0312487, US 2011/0312488, US 2011/0313212, US 2011/0313210, US 2011/0313209, US 2011/0313208, and US 2011/0312050. These applications to common inventors propose a continuous process based only upon batch autoclave results demonstrating high catalytic selectivity to ethylene glycol. However, the high ethylene glycol yields depend upon the purity of the cellulose feedstock which will intuitively cleave into 3 units of ethylene glycol. Of the experiments listed, the experiments using a feedstock closest to a biomass feedstock as found in the industrial or natural environment is bleached pulp. However, bleached pulp only produced a yield of 37%. When hemi-cellulose is used (xylose), the results are expected to be shifted much more away from ethylene glycol to propylene glycol. While the continuous process is theoretically described, the application fails to disclose an enabling continuous process. For example, the disclosure states that “[m]aterials [of a continuous] process must be capable of being transported from a low pressure source into the reaction zone, and products must be capable of being transported from the reaction zone to the product recovery zone. Depending upon the mode of operation, residual solids, if any, must be capable of being removed from the reaction zone.” This discloses the intuitively obvious requirement to operate a continuous process but the statement fails to teach one of ordinary skill how to achieve those requirements. Nowhere in the application is this essential problem discussed or solved. In fact, during the discussion of FIG. 2 of the publication, the temperature and pressure conditions are discussed without any disclosure as to how the slurry can be raised to the listed pressure of 1800 psig, or even 200 psig. When considering the transport problem, which, as of 2006, has existed since the oil embargo of 1973, a disclosure telling one of ordinary skill that transport of materials is critical can hardly be considered enabling.
These series of applications also disclose to keep the water in the reaction zone in the liquid phase. In the batch autoclave this occurs due to the sealed nature. However, it fails to disclose how this is done, or even if it can be done, in a continuous process.
In order to avoid the problems of pumping and charging as noted, but not solved, in the above applications and publications, dissolution of the lignin is proposed. WO 2011/117705 relies upon dissolving the lignin so that the material can be charged as a liquid taking full advantage of the check valve and high pressure liquid charging systems. In fact, according to WO 2011/117705, “the only limit [is] that the lignin fed to the hydrogenolysis reaction is well dissolved, at the feeding temperature, in said solvent.”
There exists therefore the need for a properly enabling disclosure of how to continuously convert lignin which includes the handling, charging, and essential conditions for the process to be carried out. These conditions and steps are believed both novel and inventive and for the first time experimentally enabled.